The goal of this study is to examine how participation in the Building Strong Families (BSF) intervention caused families to experience reductions in three different forms of familyinstability (e.g., financial, family structure, romantic relationship quality), that in turn bolster child development via stronger father involvement and higher quality coparenting relationships. This project includes three specific aims: (1) To examine the associations between participation in BSF and financial, family structure, and romantic relationship instability out to 36 months post-intervention; (2) To examine the extent to which reductions in each form of family instability mediate the effects of the BSF intervention on father involvement and coparenting quality at 36 months post-intervention; and (3) To examine the extent to which father involvement and coparenting quality mediate associations between each form of instability and children's behavior problems and language development at 36 months post-intervention. By examining multiple forms of family instability as intervention pathways, the study will inform future intervention work aimed at strengthening relationships and wellbeing among economically disadvantaged families across the transition to parenthood. Sample: Participants in the BSF dataset that have data on all relevant study variables Measures: Financial Instability Indexes ? Financial Instability ? Family Structure Instability ? Romantic Relationship Quality Instability Family Processes - Father Involvement Responsibility - Accessibility -Engagement - Coparenting Child Development Outcomes ? Behavior Problems ? Child Language